Traffic Signal Inventory

BETA performed a comprehensive signal inventory project for the Town of Tewksbury. We utilized the town’s GIS mapping to establish an initial base plan for all the project signalized intersection locations to be evaluated and inventoried. The GIS mapping platform provided a cost-effective way to perform the inventory and it also served as a long-term inventory program for the town for future traffic equipment maintenance updates. We developed improvement conceptual plans as part of the project scope of work. The field plans included a “Check List” of features to be identified to ensure that pertinent data were not overlooked. The “Check List” included supplementing the base mapping in AutoCAD to include key features of each intersection on the plans to note number of lanes, lane use, general cross-section, wheelchair ramps, pavement markings, regulatory signs, and location of traffic signal equipment (vehicular and pedestrian). This information was used to evaluate Manual on Uniform Traffic Control Devices (MUTCD) compliance. Additionally, accessible Pedestrian Signals (APS) were evaluated and identified for ADA compliance.

The inventory forms were structured to enter data in sequence and in a format that is consistent for the data requirements for this project. The items inventoried include the following:

• Controller, cabinet, and ancillary equipment
• Vehicular and pedestrian signal heads (size, type, location and number)
• Signal posts, mast arms, and span wires
• Pedestrian push buttons
• Accessible Pedestrian Signals (APS)
• Countdown pedestrian signals
• Regulatory signing (“No Turn on Red,” etc.)
• Signal phasing and timing
• Detectors
• Pre-emption
• Interconnection
• Safety issues
• Traffic operational deficiencies

BETA met with town officials who are familiar with the existing traffic signal installations to aide in the development of the GIS based inventory program and provide direction for locations of existing documentation and base mapping in the town GIS mapping system. The meeting goals were to benefit from the knowledge of the following stakeholders:

• Traffic signal maintenance staff would know the background of equipment failure and replacement/maintenance costs
• Town key personnel to gain understanding of signal performance, in terms of vehicle flow, pedestrian accessibility (Countdown, APS equipment, and effectiveness), and safety
• The town enforcement personnel to have knowledge relating to crash history and of recurrent violations that might be related to outdated or ineffective signal equipment